1. Field of the Invention
The present invention relates generally to a grease applicator that is employed to apply grease to mechanical elements, such as a bearing, and in particular to a pneumatically operated grease applicator in which grease is supplied and driven to cover over the bearing by pneumatic force.
2. The Related Art
Bearings are commonly employed in heavy machinery to support relative displacement and rotation between mechanical elements. Lubrication is one of the most important factors for maintaining operation and service life of the bearing. Lubrication of the bearing is commonly done by manually applying grease into and over the bearing. Workers apply the grease to the bearing by bear hands or hands with gloves. This often causes contamination of articles surrounding the working site or the dresses of the workers by being unexpected or accidentally contacted by the workers' hands.
A grease applicator, as shown in FIGS. 1-3, is developed to solve the problem of contamination by the grease. This conventional grease applicator, which is broadly designated with reference numeral 1 in the drawings, comprises a receptacle 10 having a top opening (not labeled) through which a bearing retainer 11 is deposited into the receptacle 10 with a spring arranged therebetween to provide a biasing force. The grease retainer 11 has a top in which a truncated conic recess having a flat bottom is defined. An axle 111 extends from the bottom of the conic recess and is substantially concentric with respect to the conic recess. A bearing 3, on which grease is to be applied, is loosely fit over the axle and positioned in the conic recess. Through holes 113 are defined in the bottom of the conic recess and are in communication between upper and lower sides of the retainer 11. The axle 111 defines a bore through which grease is fed into the space inside the receptacle 10 below the retainer 11 by a grease gun 2.
A presser 12 has a central hole 121 removably fit over the axle 111 to allow for threading engagement between extending external thread formed on the axle 111 and internal thread formed inside the hole 121. This fixes the presser 12 to the axle 111. A hand pressing block 120 is formed on a top portion of the pressure 12 and is sized to project outside the receptacle 11 to receive a pressing force applied to the presser 12 by a hand positioned on the hand pressing block 120.
By applying a pressing force to the presser 12, the bearing retainer 11 is depressed deeply into the receptacle 10, which induces a pressure inside the grease. Thus, the grease is forced to pass through the holes 113 into the conic recess. Eventually, a sufficient amount of grease flows into the conic recess and floods over and fills into the bearing 3 positioned in the conic recess.
Further, a dustproof cover 13 is selectively positioned on the top opening to shield the receptacle 10 from dust.
Such a conventional device has several drawbacks:
(A) The operation of the device is based on the amount of grease fed into the receptacle 10, and such an amount is limited. Once the grease is consumed up, the operation of applying grease must be interrupted and the bearing and the bearing retainer removed in order to replenish grease into the receptacle. The retainer is then put back into the receptacle after the replenishment of grease. Such a removing and depositing-back process of the retainer is quite likely to cause undesired contamination both inside and outside the receptacle. Further, the requirement for frequent replenishment of grease makes it impossible to consecutively apply grease to a number of bearings.
(B) The axle 111 is mechanically weak, for the axle 111 is hollow for replenishment of grease into the receptacle 10. In addition, the axle 111 must bears the depressing force from the operator's hand. These two factors together make the axle 111 easily broken, shortening the service life of the grease applicator.
(C) Clearance or gap is present between the inside surface of the side wall of the receptacle 10 and the presser 12, which causes severe leakage of grease out of the receptacle. Substantial replenishment of grease is required during the operation of the grease applicator. This means a great waste of grease.
(D) The operator must continuously apply a pressure to the presser with his or her hand. This often causes fatigue of the operator's hand and lowers down the operation efficiency.
Thus, it is desired to have an improved grease applicator that overcomes the above discussed drawbacks of the conventional grease applicators.